this rule needs to be removed. Cytochromes are a widespread class of proteins essential for the life of almost all organisms,and are involved in complexes for electron transport and related metabolic pathways in mitochondrion, cholorplasts or bacterial membranes
-e.g. cytochrome b6f complex in chloroplasts/cyanobacteria.
GO:0017004 "cytochrome complex assembly" only_in NCBITaxon:2759 "Eukaryota"
Reported by: eboyce
Original Ticket: geneontology/annotation-issues/756